The Experts below are selected from a list of 621 Experts worldwide ranked by ideXlab platform
Thomas G Cotter - One of the best experts on this subject based on the ideXlab platform.
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Norgestrel a progesterone analogue promotes significant long term neuroprotection of cone photoreceptors in a mouse model of retinal disease
Investigative Ophthalmology & Visual Science, 2019Co-Authors: Sarah L Roche, Nicolás Cuenca, Oksana Kutsyr, Thomas G CotterAbstract:Purpose Retinitis pigmentosa (RP) refers to a group of inherited blinding retinal diseases, whereby the death of mutated rod photoreceptors is followed closely by the death of cone photoreceptors. Cone cell death can be hugely debilitating as color/daytime vision becomes impaired. Thus, treatments that are effective against cone cell death are urgently needed. Our research has been working toward development of a neuroprotective treatment for RP. We have previously demonstrated significant neuroprotective properties of Norgestrel, a progesterone analogue, in the mouse retina. The current study further investigates the potential of Norgestrel as a treatment for RP, with a focus on long-term preservation of cone photoreceptors. Methods Using the well-established rd10 mouse model of RP, we administered a Norgestrel-supplemented diet at postnatal day (P)30, following widespread loss of rod photoreceptors and at the outset of cone degeneration. We subsequently assessed cone cell morphology and retinal function at P50, P60, and P80, using immunohistochemistry, electroretinograph recordings, and optomotor testing. Results While cone cell degeneration was widespread in the untreated rd10 retina, we observed profound preservation of cone photoreceptor morphology in the Norgestrel-treated mice for at least 50 days, out to P80. This was demonstrated by up to 28-fold more cone arrestin-positive photoreceptors. This protection transpired to functional preservation at all ages. Conclusions This work presents Norgestrel as an incredibly promising long-term neuroprotective compound for the treatment of RP. Crucially, Norgestrel could be used in the mid-late stages of the disease to protect remaining cone cells and help preserve color/daytime vision.
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pro survival redox signalling in progesterone mediated retinal neuroprotection
European Journal of Neuroscience, 2017Co-Authors: Ana Ruiz M Lopez, Sarah L Roche, Alice Wyse C Jackson, Jennifer N Moloney, Ashleigh M Byrne, Thomas G CotterAbstract:Retinitis pigmentosa (RP) is a group of hereditary retinal diseases, characterised by photoreceptor cell loss. Despite a substantial understanding of the mechanisms leading to cell death, an effective therapeutic strategy is sought. Our laboratory has previously demonstrated the neuroprotective properties of Norgestrel, a progesterone analogue, in the degenerating retina, mediated in part by the neurotrophic factor basic fibroblast growth factor (bFGF). In other retinal studies, we have also presented a pro-survival role for reactive oxygen species (ROS), downstream of bFGF. Thus, we hypothesized that Norgestrel utilises bFGF-driven ROS production to promote photoreceptor survival. Using the 661W photoreceptor-like cell line, we now show that Norgestrel, working through progesterone receptor membrane complex 1 (PGRMC1); generates an early burst of pro-survival bFGF-induced ROS. Using the rd10 mouse model of RP, we confirm that Norgestrel induces a similar early pro-survival increase in retinal ROS. Norgestrel-driven protection in the rd10 retina was attenuated in the presence of antioxidants. This study therefore presents an essential role for ROS signalling in Norgestrel-mediated neuroprotection in vitro and demonstrates that Norgestrel employs a similar pro-survival mechanism in the degenerating retina.
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Fractalkine-CX3CR1 signaling is critical for progesterone-mediated neuroprotection in the retina
Scientific Reports, 2017Co-Authors: Sarah L Roche, Ashleigh M Byrne, Alice C. Wyse-jackson, Ana M. Ruiz-lopez, Thomas G CotterAbstract:Retinitis pigmentosa (RP) encompasses a group of retinal diseases resulting in photoreceptor loss and blindness. We have previously shown in the rd10 mouse model of RP, that rd10 microglia drive degeneration of viable neurons. Norgestrel, a progesterone analogue, primes viable neurons against potential microglial damage. In the current study we wished to investigate this neuroprotective effect further. We were particularly interested in the role of fractalkine-CX3CR1 signaling, previously shown to mediate photoreceptor-microglia crosstalk and promote survival in the rd10 retina. Norgestrel upregulates fractalkine-CX3CR1 signaling in the rd10 retina, coinciding with photoreceptor survival. We show that Norgestrel-treated photoreceptor-like cells, 661Ws, and C57 explants modulate rd10 microglial activity in co-culture, resulting in increased photoreceptor survival. Assessment of Norgestrel’s neuroprotective effects when fractalkine was knocked-down in 661 W cells and release of fractalkine was reduced in rd10 explants confirms a crucial role for fractalkine-CX3CR1 signaling in Norgestrel-mediated neuroprotection. To further understand the role of fractalkine in neuroprotection, we assessed the release of 40 cytokines in fractalkine-treated rd10 microglia and explants. In both cases, treatment with fractalkine reduced a variety of pro-inflammatory cytokines. These findings further our understanding of Norgestrel’s neuroprotective properties, capable of modulating harmful microglial activity indirectly through photoreceptors, leading to increased neuroprotection.
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the synthetic progestin Norgestrel modulates nrf2 signaling and acts as an antioxidant in a model of retinal degeneration
Redox biology, 2016Co-Authors: Ashleigh M Byrne, Sarah L Roche, Jennifer N Moloney, Ana M Ruizlopez, Alice C Wysejackson, Thomas G CotterAbstract:Retinitis pigmentosa (RP) is one of the most common retinal degenerative conditions affecting people worldwide, and is currently incurable. It is characterized by the progressive loss of photoreceptors, in which the death of rod cells leads to the secondary death of cone cells; the cause of eventual blindness. As rod cells die, retinal-oxygen metabolism becomes perturbed, leading to increased levels of reactive oxygen species (ROS) and thus oxidative stress; a key factor in the secondary death of cones. In this study, Norgestrel, an FDA-approved synthetic analog of progesterone, was found to be a powerful neuroprotective antioxidant, preventing light-induced ROS in photoreceptor cells, and subsequent cell death. Norgestrel also prevented light-induced photoreceptor morphological changes that were associated with ROS production, and that are characteristic of RP. Further investigation showed that Norgestrel acts via post-translational modulation of the major antioxidant transcription factor Nrf2; bringing about its phosphorylation, subsequent nuclear translocation, and increased levels of its effector protein superoxide dismutase 2 (SOD2). In summary, these results demonstrate significant protection of photoreceptor cells from oxidative stress, and underscore the potential of Norgestrel as a therapeutic option for RP.
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the synthetic progestin Norgestrel acts to increase lif levels in the rd10 mouse model of retinitis pigmentosa
Molecular Vision, 2016Co-Authors: Ashleigh M Byrne, Sarah L Roche, Alice Wyse C Jackson, Ana M Ruizlopez, Thomas G CotterAbstract:Purpose: Retinal degenerative conditions affect thousands of people worldwide. Retinitis pigmentosa (RP) is among the most common, but it is currently incurable. It is characterized by the progressive death of photoreceptor cells, eventually leading to blindness. Neurotrophic factors play an important role in such retinopathies, and much research has been performed on their use as treatments. Our group previously demonstrated the ability of the synthetic progestin Norgestrel to rescue photoreceptors from cell death, the mechanism of which is believed to include upregulation of the neurotrophic factor basic fibroblast growth factor (bFGF). The objective of the present study was to investigate whether the protection provided by Norgestrel is likely to be mediated by other neurotrophins. Methods: The 661W photoreceptor cells and retinal explants from P30 to P40 wild-type (wt) C57BL/6 mice were treated with Norgestrel over time. Homozygous rd10/rd10 mice that mimic the human form of RP were fed either a control or a Norgestrel-containing diet. Changes in neurotrophic factor expression in response to Norgestrel were detected with real-time PCR, western blotting, or immunofluorescence staining. Using specific siRNA, leukemia inhibitory factor (Lif) expression was knocked down in 661W photoreceptor cells that were stressed by serum starvation. Cells were treated with Norgestrel followed by measurement of cell viability with (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay. Results: LIF, a potent neuroprotective cytokine, was found to be upregulated in response to Norgestrel in vitro and in vivo. Upregulation of LIF in degenerating rd10 retinas coincided with preservation of the photoreceptor layer. We also found LIF was necessary for the Norgestrel-mediated rescue of stressed photoreceptor cells from cell death in vitro. Conclusions: LIF was upregulated in response to Norgestrel in all models studied and is necessary for the protective effects of Norgestrel in vitro. The increase in LIF expression in rd10 mice undergoing retinal degeneration was concurrent with rescue of the photoreceptor cell layer. These results highlight the ability of Norgestrel to induce prosurvival molecules in the compromised retina, underlining Norgestrel’s potential as a viable drug for treatment of RP.
Sarah L Roche - One of the best experts on this subject based on the ideXlab platform.
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Norgestrel a progesterone analogue promotes significant long term neuroprotection of cone photoreceptors in a mouse model of retinal disease
Investigative Ophthalmology & Visual Science, 2019Co-Authors: Sarah L Roche, Nicolás Cuenca, Oksana Kutsyr, Thomas G CotterAbstract:Purpose Retinitis pigmentosa (RP) refers to a group of inherited blinding retinal diseases, whereby the death of mutated rod photoreceptors is followed closely by the death of cone photoreceptors. Cone cell death can be hugely debilitating as color/daytime vision becomes impaired. Thus, treatments that are effective against cone cell death are urgently needed. Our research has been working toward development of a neuroprotective treatment for RP. We have previously demonstrated significant neuroprotective properties of Norgestrel, a progesterone analogue, in the mouse retina. The current study further investigates the potential of Norgestrel as a treatment for RP, with a focus on long-term preservation of cone photoreceptors. Methods Using the well-established rd10 mouse model of RP, we administered a Norgestrel-supplemented diet at postnatal day (P)30, following widespread loss of rod photoreceptors and at the outset of cone degeneration. We subsequently assessed cone cell morphology and retinal function at P50, P60, and P80, using immunohistochemistry, electroretinograph recordings, and optomotor testing. Results While cone cell degeneration was widespread in the untreated rd10 retina, we observed profound preservation of cone photoreceptor morphology in the Norgestrel-treated mice for at least 50 days, out to P80. This was demonstrated by up to 28-fold more cone arrestin-positive photoreceptors. This protection transpired to functional preservation at all ages. Conclusions This work presents Norgestrel as an incredibly promising long-term neuroprotective compound for the treatment of RP. Crucially, Norgestrel could be used in the mid-late stages of the disease to protect remaining cone cells and help preserve color/daytime vision.
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pro survival redox signalling in progesterone mediated retinal neuroprotection
European Journal of Neuroscience, 2017Co-Authors: Ana Ruiz M Lopez, Sarah L Roche, Alice Wyse C Jackson, Jennifer N Moloney, Ashleigh M Byrne, Thomas G CotterAbstract:Retinitis pigmentosa (RP) is a group of hereditary retinal diseases, characterised by photoreceptor cell loss. Despite a substantial understanding of the mechanisms leading to cell death, an effective therapeutic strategy is sought. Our laboratory has previously demonstrated the neuroprotective properties of Norgestrel, a progesterone analogue, in the degenerating retina, mediated in part by the neurotrophic factor basic fibroblast growth factor (bFGF). In other retinal studies, we have also presented a pro-survival role for reactive oxygen species (ROS), downstream of bFGF. Thus, we hypothesized that Norgestrel utilises bFGF-driven ROS production to promote photoreceptor survival. Using the 661W photoreceptor-like cell line, we now show that Norgestrel, working through progesterone receptor membrane complex 1 (PGRMC1); generates an early burst of pro-survival bFGF-induced ROS. Using the rd10 mouse model of RP, we confirm that Norgestrel induces a similar early pro-survival increase in retinal ROS. Norgestrel-driven protection in the rd10 retina was attenuated in the presence of antioxidants. This study therefore presents an essential role for ROS signalling in Norgestrel-mediated neuroprotection in vitro and demonstrates that Norgestrel employs a similar pro-survival mechanism in the degenerating retina.
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Fractalkine-CX3CR1 signaling is critical for progesterone-mediated neuroprotection in the retina
Scientific Reports, 2017Co-Authors: Sarah L Roche, Ashleigh M Byrne, Alice C. Wyse-jackson, Ana M. Ruiz-lopez, Thomas G CotterAbstract:Retinitis pigmentosa (RP) encompasses a group of retinal diseases resulting in photoreceptor loss and blindness. We have previously shown in the rd10 mouse model of RP, that rd10 microglia drive degeneration of viable neurons. Norgestrel, a progesterone analogue, primes viable neurons against potential microglial damage. In the current study we wished to investigate this neuroprotective effect further. We were particularly interested in the role of fractalkine-CX3CR1 signaling, previously shown to mediate photoreceptor-microglia crosstalk and promote survival in the rd10 retina. Norgestrel upregulates fractalkine-CX3CR1 signaling in the rd10 retina, coinciding with photoreceptor survival. We show that Norgestrel-treated photoreceptor-like cells, 661Ws, and C57 explants modulate rd10 microglial activity in co-culture, resulting in increased photoreceptor survival. Assessment of Norgestrel’s neuroprotective effects when fractalkine was knocked-down in 661 W cells and release of fractalkine was reduced in rd10 explants confirms a crucial role for fractalkine-CX3CR1 signaling in Norgestrel-mediated neuroprotection. To further understand the role of fractalkine in neuroprotection, we assessed the release of 40 cytokines in fractalkine-treated rd10 microglia and explants. In both cases, treatment with fractalkine reduced a variety of pro-inflammatory cytokines. These findings further our understanding of Norgestrel’s neuroprotective properties, capable of modulating harmful microglial activity indirectly through photoreceptors, leading to increased neuroprotection.
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the synthetic progestin Norgestrel modulates nrf2 signaling and acts as an antioxidant in a model of retinal degeneration
Redox biology, 2016Co-Authors: Ashleigh M Byrne, Sarah L Roche, Jennifer N Moloney, Ana M Ruizlopez, Alice C Wysejackson, Thomas G CotterAbstract:Retinitis pigmentosa (RP) is one of the most common retinal degenerative conditions affecting people worldwide, and is currently incurable. It is characterized by the progressive loss of photoreceptors, in which the death of rod cells leads to the secondary death of cone cells; the cause of eventual blindness. As rod cells die, retinal-oxygen metabolism becomes perturbed, leading to increased levels of reactive oxygen species (ROS) and thus oxidative stress; a key factor in the secondary death of cones. In this study, Norgestrel, an FDA-approved synthetic analog of progesterone, was found to be a powerful neuroprotective antioxidant, preventing light-induced ROS in photoreceptor cells, and subsequent cell death. Norgestrel also prevented light-induced photoreceptor morphological changes that were associated with ROS production, and that are characteristic of RP. Further investigation showed that Norgestrel acts via post-translational modulation of the major antioxidant transcription factor Nrf2; bringing about its phosphorylation, subsequent nuclear translocation, and increased levels of its effector protein superoxide dismutase 2 (SOD2). In summary, these results demonstrate significant protection of photoreceptor cells from oxidative stress, and underscore the potential of Norgestrel as a therapeutic option for RP.
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the synthetic progestin Norgestrel acts to increase lif levels in the rd10 mouse model of retinitis pigmentosa
Molecular Vision, 2016Co-Authors: Ashleigh M Byrne, Sarah L Roche, Alice Wyse C Jackson, Ana M Ruizlopez, Thomas G CotterAbstract:Purpose: Retinal degenerative conditions affect thousands of people worldwide. Retinitis pigmentosa (RP) is among the most common, but it is currently incurable. It is characterized by the progressive death of photoreceptor cells, eventually leading to blindness. Neurotrophic factors play an important role in such retinopathies, and much research has been performed on their use as treatments. Our group previously demonstrated the ability of the synthetic progestin Norgestrel to rescue photoreceptors from cell death, the mechanism of which is believed to include upregulation of the neurotrophic factor basic fibroblast growth factor (bFGF). The objective of the present study was to investigate whether the protection provided by Norgestrel is likely to be mediated by other neurotrophins. Methods: The 661W photoreceptor cells and retinal explants from P30 to P40 wild-type (wt) C57BL/6 mice were treated with Norgestrel over time. Homozygous rd10/rd10 mice that mimic the human form of RP were fed either a control or a Norgestrel-containing diet. Changes in neurotrophic factor expression in response to Norgestrel were detected with real-time PCR, western blotting, or immunofluorescence staining. Using specific siRNA, leukemia inhibitory factor (Lif) expression was knocked down in 661W photoreceptor cells that were stressed by serum starvation. Cells were treated with Norgestrel followed by measurement of cell viability with (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay. Results: LIF, a potent neuroprotective cytokine, was found to be upregulated in response to Norgestrel in vitro and in vivo. Upregulation of LIF in degenerating rd10 retinas coincided with preservation of the photoreceptor layer. We also found LIF was necessary for the Norgestrel-mediated rescue of stressed photoreceptor cells from cell death in vitro. Conclusions: LIF was upregulated in response to Norgestrel in all models studied and is necessary for the protective effects of Norgestrel in vitro. The increase in LIF expression in rd10 mice undergoing retinal degeneration was concurrent with rescue of the photoreceptor cell layer. These results highlight the ability of Norgestrel to induce prosurvival molecules in the compromised retina, underlining Norgestrel’s potential as a viable drug for treatment of RP.
Virgil Craig Jordan - One of the best experts on this subject based on the ideXlab platform.
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Norgestrel and gestodene stimulate breast cancer cell growth through an oestrogen receptor mediated mechanism
British Journal of Cancer, 1993Co-Authors: William H. Catherino, Meei Huey Jeng, Virgil Craig JordanAbstract:There is great concern over the long-term influence of oral contraceptives on the development of breast cancer in women. Oestrogens are known to stimulate the growth of human breast cancer cells, and this laboratory has previously reported (Jeng & Jordan, 1991) that the 19-norprogestin norethindrone could stimulate the proliferation of MCF-7 human breast cancer cells. We studied the influence of the 19-norprogestins Norgestrel and gestodene compared to a 'non' 19-norprogestin medroxyprogesterone acetate (MPA) on MCF-7 cell proliferation. The 19-norprogestins stimulated proliferation at a concentration of 10(-8) M, while MPA could not stimulate proliferation at concentrations as great as 3 x 10(-6) M. The stimulatory activity of the 19-norprogestins could be blocked by the antioestrogen ICI 164,384, but not by the antiprogestin RU486. Transfection studies with the reporter plasmids containing an oestrogen response element or progesterone response element (vitERE-CAT, pS2ERE-CAT, and PRE15-CAT) were performed to determine the intracellular action of Norgestrel and gestodene. The 19-norprogestins stimulated the vitERE-CAT activity maximally at 10(-6) M, and this stimulation was inhibited by the addition of ICI 164,384. MPA did not stimulate vitERE-CAT activity. A single base pair alteration in the palindromic sequence of vitERE (resulting in the pS2ERE) led to a dramatic decrease in CAT expression by the 19-norprogestins, suggesting that the progestin activity required specific response element base sequencing. PRE15-CAT activity was stimulated by Norgestrel, gestodene and MPA at concentrations well below growth stimulatory activity. This stimulation could be blocked by RU486. These studies suggest that the 19-norprogestins Norgestrel and gestodene stimulate MCF-7 breast cancer cell growth by activating the oestrogen receptor.
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Norgestrel and gestodene stimulate breast cancer cell growth through an oestrogen receptor mediated mechanism
British Journal of Cancer, 1993Co-Authors: William H. Catherino, Meei Huey Jeng, Virgil Craig JordanAbstract:There is great concern over the long-term influence of oral contraceptives on the development of breast cancer in women. Oestrogens are known to stimulate the growth of human breast cancer cells, and this laboratory has previously reported (Jeng & Jordan, 1991) that the 19-norprogestin norethindrone could stimulate the proliferation of MCF-7 human breast cancer cells. We studied the influence of the 19-norprogestins Norgestrel and gestodene compared to a 'non' 19-norprogestin medroxyprogesterone acetate (MPA) on MCF-7 cell proliferation. The 19-norprogestins stimulated proliferation at a concentration of 10(-8) M, while MPA could not stimulate proliferation at concentrations as great as 3 x 10(-6) M. The stimulatory activity of the 19-norprogestins could be blocked by the antioestrogen ICI 164,384, but not by the antiprogestin RU486. Transfection studies with the reporter plasmids containing an oestrogen response element or progesterone response element (vitERE-CAT, pS2ERE-CAT, and PRE15-CAT) were performed to determine the intracellular action of Norgestrel and gestodene. The 19-norprogestins stimulated the vitERE-CAT activity maximally at 10(-6) M, and this stimulation was inhibited by the addition of ICI 164,384. MPA did not stimulate vitERE-CAT activity. A single base pair alteration in the palindromic sequence of vitERE (resulting in the pS2ERE) led to a dramatic decrease in CAT expression by the 19-norprogestins, suggesting that the progestin activity required specific response element base sequencing. PRE15-CAT activity was stimulated by Norgestrel, gestodene and MPA at concentrations well below growth stimulatory activity. This stimulation could be blocked by RU486. These studies suggest that the 19-norprogestins Norgestrel and gestodene stimulate MCF-7 breast cancer cell growth by activating the oestrogen receptor.
Ashleigh M Byrne - One of the best experts on this subject based on the ideXlab platform.
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pro survival redox signalling in progesterone mediated retinal neuroprotection
European Journal of Neuroscience, 2017Co-Authors: Ana Ruiz M Lopez, Sarah L Roche, Alice Wyse C Jackson, Jennifer N Moloney, Ashleigh M Byrne, Thomas G CotterAbstract:Retinitis pigmentosa (RP) is a group of hereditary retinal diseases, characterised by photoreceptor cell loss. Despite a substantial understanding of the mechanisms leading to cell death, an effective therapeutic strategy is sought. Our laboratory has previously demonstrated the neuroprotective properties of Norgestrel, a progesterone analogue, in the degenerating retina, mediated in part by the neurotrophic factor basic fibroblast growth factor (bFGF). In other retinal studies, we have also presented a pro-survival role for reactive oxygen species (ROS), downstream of bFGF. Thus, we hypothesized that Norgestrel utilises bFGF-driven ROS production to promote photoreceptor survival. Using the 661W photoreceptor-like cell line, we now show that Norgestrel, working through progesterone receptor membrane complex 1 (PGRMC1); generates an early burst of pro-survival bFGF-induced ROS. Using the rd10 mouse model of RP, we confirm that Norgestrel induces a similar early pro-survival increase in retinal ROS. Norgestrel-driven protection in the rd10 retina was attenuated in the presence of antioxidants. This study therefore presents an essential role for ROS signalling in Norgestrel-mediated neuroprotection in vitro and demonstrates that Norgestrel employs a similar pro-survival mechanism in the degenerating retina.
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Fractalkine-CX3CR1 signaling is critical for progesterone-mediated neuroprotection in the retina
Scientific Reports, 2017Co-Authors: Sarah L Roche, Ashleigh M Byrne, Alice C. Wyse-jackson, Ana M. Ruiz-lopez, Thomas G CotterAbstract:Retinitis pigmentosa (RP) encompasses a group of retinal diseases resulting in photoreceptor loss and blindness. We have previously shown in the rd10 mouse model of RP, that rd10 microglia drive degeneration of viable neurons. Norgestrel, a progesterone analogue, primes viable neurons against potential microglial damage. In the current study we wished to investigate this neuroprotective effect further. We were particularly interested in the role of fractalkine-CX3CR1 signaling, previously shown to mediate photoreceptor-microglia crosstalk and promote survival in the rd10 retina. Norgestrel upregulates fractalkine-CX3CR1 signaling in the rd10 retina, coinciding with photoreceptor survival. We show that Norgestrel-treated photoreceptor-like cells, 661Ws, and C57 explants modulate rd10 microglial activity in co-culture, resulting in increased photoreceptor survival. Assessment of Norgestrel’s neuroprotective effects when fractalkine was knocked-down in 661 W cells and release of fractalkine was reduced in rd10 explants confirms a crucial role for fractalkine-CX3CR1 signaling in Norgestrel-mediated neuroprotection. To further understand the role of fractalkine in neuroprotection, we assessed the release of 40 cytokines in fractalkine-treated rd10 microglia and explants. In both cases, treatment with fractalkine reduced a variety of pro-inflammatory cytokines. These findings further our understanding of Norgestrel’s neuroprotective properties, capable of modulating harmful microglial activity indirectly through photoreceptors, leading to increased neuroprotection.
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the synthetic progestin Norgestrel modulates nrf2 signaling and acts as an antioxidant in a model of retinal degeneration
Redox biology, 2016Co-Authors: Ashleigh M Byrne, Sarah L Roche, Jennifer N Moloney, Ana M Ruizlopez, Alice C Wysejackson, Thomas G CotterAbstract:Retinitis pigmentosa (RP) is one of the most common retinal degenerative conditions affecting people worldwide, and is currently incurable. It is characterized by the progressive loss of photoreceptors, in which the death of rod cells leads to the secondary death of cone cells; the cause of eventual blindness. As rod cells die, retinal-oxygen metabolism becomes perturbed, leading to increased levels of reactive oxygen species (ROS) and thus oxidative stress; a key factor in the secondary death of cones. In this study, Norgestrel, an FDA-approved synthetic analog of progesterone, was found to be a powerful neuroprotective antioxidant, preventing light-induced ROS in photoreceptor cells, and subsequent cell death. Norgestrel also prevented light-induced photoreceptor morphological changes that were associated with ROS production, and that are characteristic of RP. Further investigation showed that Norgestrel acts via post-translational modulation of the major antioxidant transcription factor Nrf2; bringing about its phosphorylation, subsequent nuclear translocation, and increased levels of its effector protein superoxide dismutase 2 (SOD2). In summary, these results demonstrate significant protection of photoreceptor cells from oxidative stress, and underscore the potential of Norgestrel as a therapeutic option for RP.
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the synthetic progestin Norgestrel acts to increase lif levels in the rd10 mouse model of retinitis pigmentosa
Molecular Vision, 2016Co-Authors: Ashleigh M Byrne, Sarah L Roche, Alice Wyse C Jackson, Ana M Ruizlopez, Thomas G CotterAbstract:Purpose: Retinal degenerative conditions affect thousands of people worldwide. Retinitis pigmentosa (RP) is among the most common, but it is currently incurable. It is characterized by the progressive death of photoreceptor cells, eventually leading to blindness. Neurotrophic factors play an important role in such retinopathies, and much research has been performed on their use as treatments. Our group previously demonstrated the ability of the synthetic progestin Norgestrel to rescue photoreceptors from cell death, the mechanism of which is believed to include upregulation of the neurotrophic factor basic fibroblast growth factor (bFGF). The objective of the present study was to investigate whether the protection provided by Norgestrel is likely to be mediated by other neurotrophins. Methods: The 661W photoreceptor cells and retinal explants from P30 to P40 wild-type (wt) C57BL/6 mice were treated with Norgestrel over time. Homozygous rd10/rd10 mice that mimic the human form of RP were fed either a control or a Norgestrel-containing diet. Changes in neurotrophic factor expression in response to Norgestrel were detected with real-time PCR, western blotting, or immunofluorescence staining. Using specific siRNA, leukemia inhibitory factor (Lif) expression was knocked down in 661W photoreceptor cells that were stressed by serum starvation. Cells were treated with Norgestrel followed by measurement of cell viability with (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay. Results: LIF, a potent neuroprotective cytokine, was found to be upregulated in response to Norgestrel in vitro and in vivo. Upregulation of LIF in degenerating rd10 retinas coincided with preservation of the photoreceptor layer. We also found LIF was necessary for the Norgestrel-mediated rescue of stressed photoreceptor cells from cell death in vitro. Conclusions: LIF was upregulated in response to Norgestrel in all models studied and is necessary for the protective effects of Norgestrel in vitro. The increase in LIF expression in rd10 mice undergoing retinal degeneration was concurrent with rescue of the photoreceptor cell layer. These results highlight the ability of Norgestrel to induce prosurvival molecules in the compromised retina, underlining Norgestrel’s potential as a viable drug for treatment of RP.
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Progesterone Attenuates Microglial-Driven Retinal Degeneration and Stimulates Protective Fractalkine-CX3CR1 Signaling
2016Co-Authors: Sarah L Roche, Ashleigh M Byrne, Alice C. Wyse-jackson, Violeta Gómez-vicente, Pedro Lax, Ana M. Ruiz-lopez, Nicolás Cuenca, Thomas G CotterAbstract:Retinitis pigmentosa (RP) is a degenerative disease leading to photoreceptor cell loss. Mouse models of RP, such as the rd10 mouse (B6.CXBl-Pde6brd10/J), have enhanced our understanding of the disease, allowing for development of potential therapeutics. In 2011, our group first demonstrated that the synthetic progesterone analogue ‘Norgestrel’ is neuroprotective in two mouse models of retinal degeneration, including the rd10 mouse. We have since elucidated several mechanisms by which Norgestrel protects stressed photoreceptors, such as upregulating growth factors. This study consequently aimed to further characterize Norgestrel’s neuroprotective effects. Specifically, we sought to investigate the role that microglia might play; for microglial-derived inflammation has been shown to potentiate neurodegeneration. Dams of post-natal day (P) 10 rd10 pups were given a Norgestrel-supplemented diet (80mg/kg). Upon weaning, pups remained on Norgestrel. Tissue was harvested from P15-P50 rd10 mice on control or Norgestrel-supplemented diet. Norgestrel-diet administration provided significant retinal protection out to P40 in rd10 mice. Alterations in microglial activity coincided with significant protection, implicating microglial changes in Norgestrel-induced neuroprotection. Utilizing primary cultures of retinal microglia and 661W photoreceptor-like cells, we show that rd10 microglia drive neuronal cell death. We reveal a novel role of Norgestrel, acting directly on microglia to reduce pro-inflammatory activation and prevent neuronal cell death. Norgestrel effectively suppresses cytokine, chemokine and danger-associated molecular pattern molecule (DAMP) expression in the rd10 retina. Remarkably, Norgestrel upregulates fractalkine-CX3CR1 signaling 1 000-fold at the RNA level, in the rd10 mouse. Fractalkine-CX3CR1 signaling has been shown to protect neurons by regulating retinal microglial activation and migration. Ultimately, these results present Norgestrel as a promising treatment for RP, with dual actions as a neuroprotective and anti-inflammatory agent in the retina.
William H. Catherino - One of the best experts on this subject based on the ideXlab platform.
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Norgestrel and gestodene stimulate breast cancer cell growth through an oestrogen receptor mediated mechanism
British Journal of Cancer, 1993Co-Authors: William H. Catherino, Meei Huey Jeng, Virgil Craig JordanAbstract:There is great concern over the long-term influence of oral contraceptives on the development of breast cancer in women. Oestrogens are known to stimulate the growth of human breast cancer cells, and this laboratory has previously reported (Jeng & Jordan, 1991) that the 19-norprogestin norethindrone could stimulate the proliferation of MCF-7 human breast cancer cells. We studied the influence of the 19-norprogestins Norgestrel and gestodene compared to a 'non' 19-norprogestin medroxyprogesterone acetate (MPA) on MCF-7 cell proliferation. The 19-norprogestins stimulated proliferation at a concentration of 10(-8) M, while MPA could not stimulate proliferation at concentrations as great as 3 x 10(-6) M. The stimulatory activity of the 19-norprogestins could be blocked by the antioestrogen ICI 164,384, but not by the antiprogestin RU486. Transfection studies with the reporter plasmids containing an oestrogen response element or progesterone response element (vitERE-CAT, pS2ERE-CAT, and PRE15-CAT) were performed to determine the intracellular action of Norgestrel and gestodene. The 19-norprogestins stimulated the vitERE-CAT activity maximally at 10(-6) M, and this stimulation was inhibited by the addition of ICI 164,384. MPA did not stimulate vitERE-CAT activity. A single base pair alteration in the palindromic sequence of vitERE (resulting in the pS2ERE) led to a dramatic decrease in CAT expression by the 19-norprogestins, suggesting that the progestin activity required specific response element base sequencing. PRE15-CAT activity was stimulated by Norgestrel, gestodene and MPA at concentrations well below growth stimulatory activity. This stimulation could be blocked by RU486. These studies suggest that the 19-norprogestins Norgestrel and gestodene stimulate MCF-7 breast cancer cell growth by activating the oestrogen receptor.
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Norgestrel and gestodene stimulate breast cancer cell growth through an oestrogen receptor mediated mechanism
British Journal of Cancer, 1993Co-Authors: William H. Catherino, Meei Huey Jeng, Virgil Craig JordanAbstract:There is great concern over the long-term influence of oral contraceptives on the development of breast cancer in women. Oestrogens are known to stimulate the growth of human breast cancer cells, and this laboratory has previously reported (Jeng & Jordan, 1991) that the 19-norprogestin norethindrone could stimulate the proliferation of MCF-7 human breast cancer cells. We studied the influence of the 19-norprogestins Norgestrel and gestodene compared to a 'non' 19-norprogestin medroxyprogesterone acetate (MPA) on MCF-7 cell proliferation. The 19-norprogestins stimulated proliferation at a concentration of 10(-8) M, while MPA could not stimulate proliferation at concentrations as great as 3 x 10(-6) M. The stimulatory activity of the 19-norprogestins could be blocked by the antioestrogen ICI 164,384, but not by the antiprogestin RU486. Transfection studies with the reporter plasmids containing an oestrogen response element or progesterone response element (vitERE-CAT, pS2ERE-CAT, and PRE15-CAT) were performed to determine the intracellular action of Norgestrel and gestodene. The 19-norprogestins stimulated the vitERE-CAT activity maximally at 10(-6) M, and this stimulation was inhibited by the addition of ICI 164,384. MPA did not stimulate vitERE-CAT activity. A single base pair alteration in the palindromic sequence of vitERE (resulting in the pS2ERE) led to a dramatic decrease in CAT expression by the 19-norprogestins, suggesting that the progestin activity required specific response element base sequencing. PRE15-CAT activity was stimulated by Norgestrel, gestodene and MPA at concentrations well below growth stimulatory activity. This stimulation could be blocked by RU486. These studies suggest that the 19-norprogestins Norgestrel and gestodene stimulate MCF-7 breast cancer cell growth by activating the oestrogen receptor.
